This invention relates in general to an electronic digital display timepiece, and in particular to a digital display electronic wristwatch having an improved correction circuit with a locking switch for preventing inadvertent correction.
Electronic digital display timepieces, namely, timepieces wherein a liquid crystal or light emitting diode display effects the display of actual time in response to timekeeping signals generated by electronic circuitry, are gaining wide popularity. As the manufacture and sale of such timepieces increases, correction circuits for easily and accurately correcting such electronic timepieces utilizing the minimum number of correction switches possible is desired. Approaches for minimizing the number of switches can fall into four general categories.
The first category is the deactivation of the seconds counter in the wristwatch when a button switch is pressed, or a crown is pulled out, the counter being restarted after each of the other digits in the timepiece is corrected. A second approach is the setting of each of the counters at zero when the crown is pulled out to thereby enable the correcting of each digit, the pushing in of the crown after correction restarting the counters.
A third approach which is similar to the above-noted approach is to allow the circuitry to continue counting when the crown or other like actuating mechanism is pulled out. Once the hour and minute digits are corrected, and the crown is pushed in to restart the mechanism, the mechanism instantly resets the seconds counter to zero and the movement begins counting. When such an approach is utilized the smallest unit of time displayed by the timepiece, such as seconds or hundreds of seconds, namely the display corresponding to the shortest period of time is reset to zero.
Finally, a variation on the above-noted methods is to reset the seconds counter to zero at the time that the crown or other like correcting mechanism is pulled out thereby causing the digit to be reset to zero instantaneously at the beginning of correction and then to correct the other digits, the seconds counter continuing to count during correction of the other digits.
Because correction of electronic timepieces is usually done by listening to a reference signal such as an announcement of time, each of the approaches detailed above is aimed at setting to zero the seconds counter and allowing same to begin counting at the reference time.
A disadvantage of electronic timepieces is that unlike mechanical display timepieces wherein the correction of time is performed by pulling out the crown and rotating same, electronic display wristwatches include push buttons or other manually operated switches which are associated with the digits of time to be displayed to thereby allow each manually operated switch to be used for the individual correction of the incorrect digits of time. Accordingly, because such push buttons and other manually operated switches are likely to be inadvertently actuated, it is necessary to provide a locking switch to protect against accidental or inadvertent correction when same is not needed.